3pt hitch backhoes. it is normally suggested to get a "sub frame" for your tractor to work with the backhoe. if you don't you are more likely to destroy or damage the 3pt hitch.
i am different than jeff9366, once a machine gets some years on it, and hours on it. things tend to go down rather quickly for resale value. i would rather put more into... over all reach / dig depth, and overall weight it can lift. (keeping within ability of the tractor to handle the backhoe)
the one thing most folks that have a backhoe want, ends up being a "thumb" for the backhoe. there are cheap mechanical (kinda pin on thumbs) that might be adjustable with spots were you pin, and then there are hydraulic version of thumbs that are more expensive.
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if you are not going to be using a backhoe a whole lot. renting a "mini ex" (mini excavator) and simply saving up jobs over a year or what ever. and go all weekend warrior when renting a unit. can be easier on some folks pocket books.
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if you were buying new, getting tractor + FEL (front end loader) + backhoe = more chance of possibly getting dealer to giving a larger discount over all. due to those three items tend to be high price ticket items. being that you already have tractor and purchasing as a later purchase your going to eat some expense.
if you were to be using the backhoe a lot. just buying a TLB (tractor loader backhoe) were you can physically due a 180 in the seat and operate backhoe, can be a major plus. vs getting off tractor and getting on backhoe seat.
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goal of above, is more along the lines is were do you want to eat the extra cash, vs how much you will use it? granted most folks like myself find many uses for a backhoe. besides digging / stump removal.